For example, a reduction in sliding resistance of slide members mounted in automobiles is desired to reduce fuel consumption of automobiles. Therefore, a structure in which the surface of a slide member is covered with a DLC (Diamond Like Carbon) film that has low frictional properties and abrasion resistance (high hardness properties) is known.
A DLC film is formed by a Direct Current Plasma CVD (Direct Current Plasma Chemical Vapor Deposition) method, for example. A direct current plasma type treatment system illustrated in Patent Document 1, for example, is used to form a DLC film. In that direct current plasma type treatment system, plasma is generated inside a treatment chamber by direct-current voltage being applied to a substrate with the inside of the treatment chamber being in a reduced pressure state of a hydrogen carbonate-based source gas atmosphere. Then the source gas is turned into plasma, and a deposition layer of DLC forms on the surface of the substrate.
Meanwhile, nitriding treatment is carried out on the surface of the substrate before the deposition of DLC according to the direct current plasma CVD method. The nitriding treatment and the forming of the deposition layer of DLC are carried out using the same treatment system, for example. That is, in the nitriding treatment, plasma is generated inside the treatment chamber by direct-current voltage being applied to the substrate in a reduced pressure state in a nitrogen gas atmosphere. Also, the nitrogen gas is turned into plasma, and a nitrided layer is formed on the surface of the substrate. The deposition layer of DLC according to the direct current plasma CVD method is formed on this nitrided layer.
The direct current plasma type system illustrated in Patent Document 1 generates plasma continuously during treatment, so the temperature of the treatment chamber (i.e., the treatment temperature) reaches 500 to 600° C. in both the nitriding treatment and the process for depositing (forming) the DLC film.